Fuse device



J. LOFGREN July 31, 1934.

FUSE DEVICE Filed Aug. 31. 1951 Patented July 3l, 1934 PATENT OFFICE y 1.1mm: I rusa nevica John Lofgren, Chicago. IIL, assigner to Balea .Manufacturing Co., Chicago, lll., a corporation of Illinois Application 1mm s1, 1931, serai No. man

My invention relates to fuse protecting devices for detachable electrical plugs having two or more prongs adapted to be inserted in corresponding holes in convenience-outlet boxes.

. 'I'hese convenience outlets are usually-installed in the wall or floor and are supplied with current from a common distributing center. Usually the circuit running from the distributing center supplies current for six or more of these outlets and 1 therefore a fuse of suillcien't capacity must be used on the circuit feeding these outlets so as to carry the combined load when all of these outlets have appliances connected to them. For instance, assuming that a bridge lamp is being used in one outlet, a radio receiver in another and an electric refrigerator in another, a ilat iron in another, and a .percolator in another, all taking current from one common fuse in the distributing center, it will be appreciated that in the event of a damaged cord, faulty insulation, or any other defect that may develop in any one of the appliances connected to this circuit that with the large size of fuse ordinarily used on this circuit, no protection is provided for any individual appliance, and as a result, serious damage may be done and in some cases, a real fire hazard is presented.

One of the objects of my invention is to provide a plug connector for a convenience outlet box provided with an individual fuse so as to give full protection to each individual plug connected to said outlet so that in the event of any powble failure in the operation of such individual plugs it is automatically cut of! from the circuit without putting the balance of the appliances in the circuit out of service and at the same time, the appliance itself is protected from further damage.

Yet another object of my invention is to provide a compact and simple type of combinedde- '4 tachabie plug and fuse protector therefor for convenience outlet boxes so as to provide a ready means for obtaining individual fuse protection for electrical appliances connected to the regular or so-called convenience outlet which is now in general use in houses, onlce buildings, hospitals, mills and factories.

Yet another object of my invention resides in providing a combined plug and fuse protector which is adapted for connection directly to the 5 appliance itself or alternatively carries or is provided with plug connecting slots' so that thedevice itself may be plugged into a convenience outlet box and another detachable plug from the appliance itself may be plugged into the device.

These and other objects of my invention will (Cl. 20G-115.5)

be apparent from a perusal of the following specification when taken in connection with the fol lowing drawing wherein Fig. 1 is a perspective view of one form of my device as applied to a convenience outlet box; H

Fig. 2 is a view oi' Fig. 1 with the cover removed;

Fig. 4 is an alternative form of the invention shown in perspective; f

Fig. 5 is a sectional view on line 5-5 of Fig. 4;

Fig. 6 is a perspective view of a modified form of my device showing its vadaptation to a detachable plug having four prongs;

Fig. 7 is a'sectional view taken through the 7l right-hand portion of the device shown in Fig. 6 showing the four fuse plugs, one for each DIOHS;

Fig. 8 is a view of a type of my device showing it provided with three prongs, and y Fig. 9 is a corresponding view showing the type with two prongs, such as illustrated in Figs. l, 2, 3, 4 and 5.

Referring now to the drawing in detail, in Figs. 1 to 9 there is illustrated the ordinary type of convenience outlet comprising the usualplate 2 adapted to be fastened to the wall or to the floor and provided with the usual spaced-apart two slots 4 and 6 which are of minimum size to recive the spaced-apart prongs of a detachable p ug.

My improved combined plug and fuse device is constructed and arranged for cio-operation with such convenience outlet and is provided with two or more prongs for insertion in said slots 4 and 8. as is well known in the art. In the type illustrated in Figs. 1 to 5 inclusive, and also in Fig. 9, my improved device comprises a relatively small, compact box or casing which is preferably formed in two parts, a bottom part 8 and a top 10 which may be suitably held together by any type of fastening means such,'for instance, as a ausw 12 which is adapted to thread into an opening 14 in a central web 16, preferably formed integrally with the bottom of the box. Since these devices may be made of a phenolic condensation product or any other suitable insulating material, this rib 16 may be moulded into the bottom oi' the box and extends as a suitable partition practicauy the entire length of the box. The top lili or lid of the box 10 is likewise of a moulded phenolic condensation product or any `othersuitable material and is lprovided with a corresponding rib so that when the lid is placed upon the bottom the two ribs will meet to form separate nl chambers for the two fuses and connections hereinafter described.

The bottom portion 8 of the box is provided with two openings spaced apart to correspond with the spacing of the slots 4 and 6 in the convenience outlet. In' the bottom of the box and in the two chambers formed by the spacing rib 16 I provide a clip comprising a sheet metal plate 18 having an integral depending leg 20 which passes through the slot in the bottom of the box and projects therefrom in the form of a prong. The clip carries two upstanding spaced-apart spring arms 22 and 24 which are suitably curved to form a springV seat therebetween for the reception of the usual metal caps on the opposite ends of the fuse. These upstanding arms are connected by an integral yoke at their bottoms which are adapted to connect and underlie the base clip 18 and a fastening screw 26 passes through the base clip 18 and through the underlying cross portion of the spring arms to fasten the assembly in position on the bottom portion of the box. At the opposite end of each of these chambers a second plate 28 is mounted. This plate likewise carries two corresponding upstand4 ing spring arms 36 and 32 attached to the plate 28 by means of a screw 34 in the same manner as hereinbefore described. This screw 34 screws into the basal portion of the box 8 to likewise fasten the clip 28 to the bottom of the box. In

addition, the clip 28 carries the usual type of bind,-

ing screw 36 to which a wire 38 is connected. A similar wire 40 is connected to the binding screw 42 on the 4corresponding clip on the other side of the bridge wall 16. It will be noted that the two clips 22 and 24, and 30 and 32 are spaced apart sufliciently to receive the metal caps on the ends of the fuse. Each connection on either side of the bridge 16 is identical, there being two outwardly projecting prongs 20 and two wire con nections 38 and 40 which are adapted to pass through the usual type of insulation casing or covering 44 for connection with any type of appliance, such as a at iron, radio set. electric ice box, vacuum cleaner, and the like.

In the use of the various types of device, when it is desired to operate the electrical appliance, the two prongs 20, such for instance as areshown in Fig. 9, are plugged into the slots 4 and 6 of the convenience outlet so that theappliance will thus be' .electrical1y connected with the source of current. Due to the fact that each prong connection and each corresponding wire has connected in series' therewith a fuse, in the event that any defect in operation, or breaking down-ot insulation occurs in the appliance, the fuses will blow out and thereby protect the appliance, and

at the same time, maintain the circuits to the other outlet boxes intact so that any other appliance connected to any one of them will be connected for operation.

In themodiiied construction shown in Figs.

-4 and 5, instead of providing the connecting plate 28 with a screw post connection such as 36 for connection Vwith the wires 38 and 40, I provide the plate 46 thereof with two upstandng clips 48 which are similar in all respects to the clips hereinbefore mentioned, except that they provide two spring jaws spaced close together to receive therebetween one of the prongs 50 of any type of connector plug such, for instance, as is shown at 52 in Fig. 4. In addition I provide the top of the box 10 with two spaced-apart slots or openings 54 and 56 to receivefthetwo prongs 50 of the plug. These slot-,S54 and 56 are directly opposite and overlie the pair of spring clips 48 hereinbefore described. It Will be understood, of course, thatthe plug 52 is provided with the usual type of two-Wire connection 58 and 60 running to the electrical appliance. The internal construction and arrangement of this type of device is exactly the same as that shown in Figs. 2 and 3 in detail, the only change made being the substitution of the two spring clips and the slots in the top of the box for the binding post 36 and the wire connections 38 and 40.

The majority of convenience outlets are equipped with two slots for the reception of connectors having two prongs. There are also some convenience outlets used that have three slots for three-wire type of connector, and also four slots for the four wire type. In Figs. 6 and 8 I have illustrated modifications of my device showing it in its adaptation for the three-pole type and the four-pole. type. In these modications the convenience outlet plate 2 is shown as provided in Fig. 6 with the four slots 62 and the box 64 is shown with four connector prongs 66. In Fig. 8 the convenience plate outlet 2 is` shown as provided with three slots 68 and my improved connector box is shown as provided with corresponding 3 prongs 76.

In Fig. 7 of the drawing I have shown the details of internal construction of my type of connector box which is provided with four prongs constructed in the manner hereinbefore described in connection with the descriptionof Figs. 2 and 3, the only difference being that the box is provided with three internal ribs 72 adapted to divide the upper and lowerhalves of the box into four internal chambers in which are located four fuse plugs. The connections are exactly the same as are shown in Figs. 2 and 3 for one modification or in Figs. 4 and 5 for the other type. In the three pronged box there will be two partitions like 72 to provide three chambers for the reception of three fuses in the manner hereinbefore described..

From the foregoing it will be appreciated that I have provided a very compact, simple and convenient type of detachable plug connector for convenience outlets and wherein each plug connector running to an appliance to be operated is protected by an individual fuse. It will, of

course. be borne in mind that the capacity of vthe fuses are adapted to vary to correspond withor slots of the convenience outlet. The grounded side of the convenience outlet box which connects to a prong will require n`o fuse and the corresponding prong within the box and its contact, in such case, can be directly connected in any desired manner.v However, I prefer to use a fuse for each prong. This is particularly advantageous in the two prong type of box shown in Fig. 9. In this construction, by using two fuses, either of the prongs 20 can be inserted in either of the slots 4 or 6, whereas if only one fuse were used in this two prong type, it would be necessary` always to insert the fuse protected prong in the live slot of the outlet box.

. thuslfully described my invention, what if) g I claim as new and desire to obtain by Letters Patent of the United States is:

1. In a device of the class described, comprising a detachable cover and base formed of insulating material, said base and cover being provided with co-operatively associated portions for providing a plurality of chambers, each chamber having an opening in the wall thereof and each chamber having a conducting plate fastened to the wall portion thereof and providedl 2. A detachable plug connector for a convenience outlet comprising an enclosing casing formed in cooperating segments divided along a longitudinal plane of cleavage, a prong carried on one segment and projecting therefrom in a direction at right angles to the plane of cleavage for insertion in a corresponding slot of the convenience outlet, a fuse clip in said casing and connected to said prong, a second fuse clip in said casing in position to form, with the mst mentioned clip, a fuse support adapted to carry an elongated fuse element in the casing in position substantially at right angles to the prong and parallel to the plane of cleavage whereby to facilitate assemblage of the fuse element in the clip, and means for electrically connecting the second clip with an external electric circuit.

JOHN LOFGREN. 

